*********************************************************** SI/USGS Weekly Volcanic Activity Report 13-19 May 2009 *********************************************************** Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Galeras, Colombia | Manam, Northeast of New Guinea (SW Pacific) | San Cristóbal, Nicaragua | West Mata, Tonga Islands (SW Pacific) Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Chaitén, Southern Chile | Dukono, Halmahera | Kilauea, Hawaii (USA) | Redoubt, Southwestern Alaska | Reventador, Ecuador | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Soufrière Hills, Montserrat | Suwanose-jima, Ryukyu Islands (Japan) | Tungurahua, Ecuador | Ubinas, Perú | Ulawun, New Britain The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. New Activity/Unrest GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4276 m On 19 May, INGEOMINAS reported that gas plumes from Galeras occasionally contained some ash during the previous four days. An overflight on 17 May revealed gas emissions emanating from multiple points inside and outside of the main crater. Some thermal anomalies surpassed 180 degrees Celsius. During 17-18 May, two M 2.9 earthquakes occurred 6 km SSE at depths of 2-3 km, and on 18 May one M 2.3 earthquake occurred at a depth of 3-5 km, 5 km SSW. The Alert Level was lowered to III (Yellow; "changes in the behavior of volcanic activity"). Geologic Summary. Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors. Source: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co// MANAM Northeast of New Guinea (SW Pacific) 4.080°S, 145.037°E; summit elev. 1807 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 13 May an ash plume from Manam rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted about 20 km SE. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html SAN CRISTOBAL Nicaragua 12.702°N, 87.004°W; summit elev. 1745 m Based on analysis of satellite imagery, the Washington VAAC reported that on 19 May a diffuse plume from San Cristóbal drifted 45 km SW. Geologic Summary. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1,745-m-high youngest cone, San Cristóbal itself (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristóbal, are of Pleistocene age. Volcán Casita contains an elongated summit crater and lies immediately E of San Cristóbal; Casita was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html WEST MATA Tonga Islands (SW Pacific) 15.10°S, 173.75°W; summit elev. -1174 m In early May, scientists aboard a NOAA Vents Program rapid-response vessel, the R/V Thompson, traveled to the Lau-Tonga region to inspect the sea floor after strong indications of eruptive activity had been detected during a November 2008 expedition. On 6 and 7 May, team members used the Jason 2 ROV to observe eruptions from two vents of West Mata, a small submarine volcanic cone in the northeast Lau Basin, about 200 km SW of Samoa. Explosive activity occurred from one end of a 5-m-long fissure at Hades vent, at a depth of 1,208 m, while pillow lavas erupted from the other end of the fissure. Glowing bubbles up to a meter in diameter also issued from the fissure. The Prometheus vent, a cinder cone located near the summit and about 100 m N of Hades, erupted explosively with nearly continuous lava fountains that ejected tephra into the water. Both vents were often obscured by sulfur gas emissions, but incandescence was visible for minutes at a time. Geologic Summary. West Mata, a submarine volcano rising to within 1174 m of the sea surface, is located in the northeast Lau Basin at the northern end of the Tonga arc. It was discovered during a 2008 NOAA Vents Program expedition to be producing hydrothermal plumes consistent with a recent eruption. A return visit in May 2009 documented explosive and effusive activity from two closely spaced vents, one at the summit, and the other on the SW rift zone. Source: NOAA PMEL Vents Program http://www.pmel.noaa.gov/vents/index.html Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on analysis of satellite imagery, the Darwin VAAC reported that during 14-19 May ash plumes from Batu Tara rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 35-75 km W, NW, and N. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that during 5-12 May gas-and-ash plumes rose up to 1.5 km from Chaitén's growing Domo Nuevo 1 and Domo Nuevo 2 lava-dome complex. Collapses originating from unstable slopes generated block-and-ash flows. Seismicity remained elevated. The Alert Level remained at Red. Based on web camera views, the Buenos Aires VAAC reported that on 13 May, a diffuse ash plume rose to an altitude of 2 km (6,500 ft) a.s.l. and drifted NE. Geologic Summary. Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m. Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/, Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analysis of satellite imagery, the Darwin VAAC reported that on 14 May an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110 km N. Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 13-19 May, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha and Kupapa'u ocean entries. The vent in Halema'uma'u crater continued to produce a predominantly white plume, occasionally tinged brown, that drifted mainly W. Various amounts of tephra, including Pele's hair and irregular pieces of vesicular glass, were retrieved from collection bins placed near the plume during the reporting period. A molten lava pool near the base of the cavity, deep below the floor of the vent, produced incandescence of variable intensity. Sounds resembling rushing gas and rockfalls were sometimes heard in the vicinity of the crater. Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/ REDOUBT Southwestern Alaska 60.485°N, 152.742°W; summit elev. 3108 m AVO reported that during 13-19 May seismicity from Redoubt had decreased from levels detected during 2-7 May, but remained above background levels. Rock avalanche events, discrete earthquakes, and minor volcanic tremor were evident in seismic data. Growth of the lava dome in the summit crater continued and vigorous steam emissions from the margins of the lava dome were seen on the web camera. Occasional rockfalls originating from unstable slopes of the lava dome produced minor ash clouds in the vicinity of the summit. Occasional incandescence was observed in nighttime images from the web camera. On 15 May, the volume of the dome was an estimated 30-60 million cubic meters. During an overflight on 16 May, scientists observed a turquoise lake along the S margin of the dome, and a hot, vigorous, and persistent fumarole on the W wall of the upper gorge. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange. Geologic Summary. Redoubt is a 3108-m-high glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. Collapse of the summit of Redoubt 10,500-13,000 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano. Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/ REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m The Washington VAAC reported that, although ash from Reventador was observed by IG on 15 May, an ash signature or a thermal anomaly was not detected in satellite imagery. Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that on 19 May an eruption from Sakura-jima produced a plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SE. Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that seismic activity at Shiveluch was above background levels during 8-15 May. Based on interpretations of seismic data, occasional ash plumes likely rose to an altitude of 5.4 km (17,700 ft) a.s.l. On 13 May, an ash plume generated by a hot avalanche was seen on video and rose to an altitude of 5 km (16,400 ft) a.s.l. Analysis of satellite imagery revealed a daily thermal anomaly from the lava dome. The Level of Concern Color Code remained at Orange. Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 8-15 May activity from the Soufrière Hills lava dome was generally at a low level. Multiple lahars traveled down several ravines during 12-15 May. Heavy rainfall caused erosion of the lava dome and pyroclastic flow deposits that were still hot; steam plumes occasionally laden with ash occurred periodically from the base of Tyre's ghaut and were visible from MVO. The Hazard Level remained at 3. Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption. Source: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/ SUWANOSE-JIMA Ryukyu Islands (Japan) 29.635°N, 129.716°E; summit elev. 799 m The Tokyo VAAC reported an explosion from Suwanose-jima on13 May, as stated by JMA. Details of possible resultant ash plumes were not reported. Based on analysis of satellite imagery and a pilot observation, the VAAC also reported that on 17 May an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent Strombolian activity from On-take, the NE summit crater, that began in 1949 and lasted nearly a half century. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, after which the island was uninhabited for about 70 years. The SW crater produced lava flows that reached the western coast in 1813, and lava flows reached the eastern coast of the island in 1884. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m The IG reported that inclement weather sometimes prevented observations of Tungurahua during 13-19 May. Roaring noises were occasionally reported. On 13 and 18 May, a fine layer of ash fell in Manzano, 8 km SW. On 15 May, explosions and sounds resembling rolling blocks were noted. An explosion generated a steam-and-ash plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted ENE. During 16-18 May, steam and steam-and-ash plumes drifted NW, W, and E. During 17-18 May, blocks were heard or seen rolling down the flanks. Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/ UBINAS Perú 16.355°S, 70.903°W; summit elev. 5672 m Based on pilot observations, analysis of satellite imagery, and SIGMET notices, the Buenos Aires VAAC reported that during 15-19 May ash plumes from Ubinas rose to altitudes of 5.5-7.6 km (18,000-25,000 ft) a.s.l. and drifted SW, NW, and SSE. Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread Plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html ULAWUN New Britain 5.05°S, 151.33°E; summit elev. 2334 m RVO reported that white vapor plumes from Ulawun's summit crater were emitted on 10 May and rose a maximum height of 1.5 km. During 10-12 May, occasional roaring and rumbling noises were reported by villagers on the SE and S sides of the volcano. Weak fluctuating incandescence was also seen by people on the S side. Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater. Source: Ima Itikarai, Rabaul Volcano Observatory (RVO) +++++++++++++++++++++++++++++++++++++ Sally Kuhn Sennert SI/USGS Weekly Volcanic Activity Report Editor Global Volcanism Program http://www.volcano.si.edu/reports/usgs/ Smithsonian Institution, National Museum of Natural History Department of Mineral Sciences, MRC-119 Washington, D.C., 20560 Phone: 202.633.1805 Fax: 202.357.2476 ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
